Single crystal material, which is the starting material for fabricating many electronic components such as semiconductor devices and solar cells, is commonly prepared using the Czochralski (“CZ”) method. Briefly, the Czochralski method involves melting polycrystalline source material, such as polycrystalline silicon (“polysilicon”), in a crucible to form a silicon melt, and then pulling a single-crystal ingot from the melt.
The Czochralski growth process is typically carried out in a sealed or enclosed housing with a controlled, inert gas flow to inhibit dust and other airborne particles from contaminating the melt. The inert gas flow is also used to evacuate gaseous products (e.g., SiO, CO, etc.) generated from reactions between the melt, the crucible, and/or the susceptor during the growth process. As gaseous products are carried away from the melt and the hot zone (e.g., heater and the crucible), the gaseous products cool and deposit and form precipitates on components of the crystal puller, often in the form of silicon carbide. Such precipitates can form blockages in a gas exhaust port of the crystal puller, resulting in reduced exhaust gas flow, increased pressure, and potential loss of zero-dislocation growth or run failures.
Known methods and crystal pulling systems for addressing and/or reducing precipitate buildup are less than optimal for certain applications. For example, current methods for addressing precipitate buildup in crystal pullers include frequently cleaning the crystal puller components, applying chemical barriers or coatings to components to inhibit deposition of gaseous products, and maintaining the exhaust port and related components at elevated temperatures to prevent condensation and precipitation of gaseous products. However, such methods typically result in significant downtime of the crystal puller, thereby decreasing throughput of crystal puller, and/or are costly and complex to implement in existing crystal pullers. Accordingly, a need exists for crystal pulling systems and methods for inhibiting precipitate build-up in the exhaust flow path of crystal pulling systems.
This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.